The interesting parts of Blighttown arise as the result of a bunch of smaller micro-decisions you make as you navigate the complex environment - not only would mapping this out take a long time, in play it's unlikely to be interesting - many smaller choices without much information to go on.
I think we're better off looking to use the aggregate result - the interesting bit where rubber meets road whilst also allowing players to meaningfully input into the end result. To do this, we can abstract these choices into a system.
As I see it there's one main decision players are making from this high-level view - how do we balance speed (i.e. splitting up and examining multiple routes to go forward) and safety (not doing that, and exploring only as a group).
First up we have an objective - either to explore some designated amount or to use the complex environment to get from point A to point B. Either way, we assign them a number. This number needs to be reached by rolling dice and keeping a cumulative score - when it is, you did the thing you were trying to do. We'll workshop some hard numbers later. Important note - once a route is known, it's known. Characters don't need to explore again.
So what dice do we roll, and how many?
Roll dice equal to the number of search parties - each search party being a distinct group. Two groups exploring? Two dice.
The sides of the dice we roll depends on how dangerous the environment is - we use the dice to trigger encounters as well as increase our score. The smaller the dice, the less progress you'll probably make per exploration, because stuff keeps happening and slowing you down.
Each roll of these dice represents a chunk of meaningful time. In traditional dungeons, this is about 10 minutes - an hour feels intuitively right for this. You could try extrapolating this up for weird 'problem-space'-crawls where each turn is a day but I don't think it'd work.
Whenever the maximum roll on an exploration dice is achieved, roll a normal encounter - but use the surprise and encounter distance rules from your retroclone of choice for each search party and the monsters. (Currently, that's Delving Deeper for me - so 2d6 x 10 feet distance without surprise, 1d6 x 10 with surprise)
If that number -1 is rolled, roll a d4 or d6 (depending on cruelty) on the following chart for some consequences.
- Lost - characters will have to explore to discover the route back.
- Separated - Search parties lose contact - yelling etc. will cause normal encounter checks...
- Circular path - negate the gain on this dice.
- or more - no consequence
Really Fucking Dangerous - d4
Dangerous - d6
Adventuresome - d8
Baby's Day Out - d10
To work out the score needed, I'd just multiply the rough number of hours it could take by five.